AU702618B2 - 4-(2-amino-6-(cyclopropylamino)-9H-purin-9-yl)-2 -cyclopentene-1-methanol succinate as antiviral agent - Google Patents

Abstract

The present invention relates to the succinate salt of (1S,4R)-<u>cis</u>-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol or a solvate thereof, to pharmaceutical formulations containing such a compound or pharmaceutical formulations, and to its use in medical therapy or in methods of treatment or prophylaxis of a viral infection, specifically human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infection.

Description

WO 96/06844 PCTIGB95/02014 -2prepared is stable, easy to isolate, for example by rapid and efficient filtration, and phamaceutically acceptable.

We have found that the advantages of the succinate salt of the above compound over the hydrochloride salts disclosed renders the succinate salt particularly suitable and advantageous to prepare on a large scale, and for use in the preparation of pharmaceutical formulations for administration to humans.

According to the first aspect of the invention there is provided the succinate salt of (1 S,4R)-cs4[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-l methanol or a solvate thereoft including a hydrate thereof, hereinafter referred to as the compound according to the invention.

Further aspects of the invention include: a) The compound of the invention for use in medical therapy, particularly in the treatment or prophylaxis of viral infections, specifically against an HIV or an HBV infection.

b) A method for the treatment or prophylaxis of a viral infection particularly an HIV or an HBV infection in a human which comprises administering to said human an effective amount of the compound according to the invention.

c) Use of a compound according to the invention in the manufacture of a medicament for the treatment or prophylaxis of a viral infection particularly an HIV or an HBV infection.

The compound of the invention is particularly useful for the prophylaxis or treatment of HIV infections.

Examples of clinical conditions caused by HIV infections which may be treated in accordance with the invention include Acquired Immune Deficiency Syndrome (AIDS) or symptoms that frequently precede AIDS, or related clinical conditions such as AIDS-related complex (ARC), progressive generalised lymphadenopathy

(PGL),

Kaposis sarcoma, thrombocytopenic purpura, AIDS related neurological conditions, WO 96/06844 PCT/GB95/02014 -3such as multiple sclerosis or tropical paraparesis and also anti-HIV antibody-positive and HIV-positive conditions including AIDS asymptomatic patients.

As an additional feature of the invention we provide a process for the preparation of the compound of the invention which comprises dissolving (lS,4R)-is-4-[2-amino-6cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-l-methanol and succinic acid in water, preferably in equimolar amounts, in a suitable solvent, for example aqueous ethanol or isopropanol. Such solutions are advantageously prepared at reflux Upon cooling to ambient temprature crystals of the compound of the invention precipitate from said solution in high yield. Optional washing and recrystallisation may be used to increase the purity of the product, if required. The compound of the invention being in a crystalline form provides a means for large scale manufacture by rapid and efficient filtration.

The compound of the invention may be administered alone or in combination with other therapeutic agents suitable in the treatment of HIV infections, such as Nucleoside Reverse Transciptase Inhibitors (NRTIs) for example zidovudine, zalcitabine, lamivudine, didanosine, stavudine, 5-chloro-2',3'-dideoxy-3'-fluorouridine and 5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine, non-NRTIs for example nevirapine and a-APA, HIV protease inhibitors for example saquinavir or VX-478, other anti-HIV agents for example soluble CD4, immune modulators for example interleukin I, erythyropoetin, tucaresol, and interferons for example a-interferon In addition the compound of the invention may be administered in combination with other therapeutic agents suitable in the treatment ofHBV infections for example lamivudine, (2R,5S)-5-fluoro-l-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine, immune modulators, and interferons as described above. Such combinations may be administered together or sequentially providing that any duration between the administration of each therapeutic agent does not diminish their additive effect.

While it is possible for the compound of the invention to be administered alone it is preferable and advantageous to present the compound of the invention as a pharmaceutical formulation, and represents a further feature of the invention. The pharmaceutical formulation comprises of the compound of the invention together with one or more acceptable carrier(s) thereto and optionally other therapeutic agents. The WO 96/06844 PCT/GB95/02014 -4carrier(s) must be "acceptable" in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipients thereof.

The compounds according to the invention may be administered by any route appropriate to the condition to be treated, suitable routes including oral, rectal, nasal, topical (including transdermal, buccal and sublingual), vaginal and parenteral (including subcutaneous, intramuscular, intravenous, intradermal, intrathecal and epidural). It will be appreciated that the preferred route may vary with, for example, the condition of the recipient.

For each of the above-indicated utilities and indications the amount required of the individual active ingredient will depend upon a number of factors including the severity of the condition to be treated and the identity of the recipient and will ultimately be at the discretion of the attendant physician. In general, however, for each of these utilities and indications, a suitable, effective dose will be in the range of 3 to 120 mg per kilogram body weight of recipient per day, preferably in the range of 6 to 90 mg per kilogram body weight per day and most preferably in the range of 15 to 60 mg per kilogram body weight per day. The dose may if desired be presented as two, three, four or more sub-doses administered at appropriate intervals throughout the day.

The formulations include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal or parenteral (including subcutaneous, intramuscular, intravenous, intradermal, intrathecal and epidural) administration. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. Such methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more accessory ingredients. In general the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product.

Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous liquid; or as an oil-in-water liquid emulsion or a WO 96/06844 PCT/GB95/02014 water-in-oil liquid emulsion. The active ingredient may also be presented as a bolus, or paste or may be contained within liposomes.

A tablet may be made by compression or moulding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine the active ingredient in a free-flowing form such as a powder or granules, optionally mixed with a binder povidone, gelatin, hydroxypropylmethyl cellulose), lubricant, inert diluent, disintegrant sodium starch glycollate, crosslinked povidone, cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl-cellulose in varying proportions to provide the desired release profile.

A capsule may be made by filling a loose or compressed powder or an appropriate filling machine, optionally with one or more additives. Examples of suitable additives include binders such as povidone, gelatin, lubricants, inert diluents, disintegrants as for tablets. Capsules may also be formulated to contain pellets or discrete sub-units to provide slow or controlled release of the outline ingredient. This can be achieved by extruding and spheronising a wet mixture of the drug plus an extrusion acid (e.g.

microcrystalline cellulose) plus a diluent such as lactose. The spheroids thus produced can be coated with a semi-permeable membrane ethyl cellulose, Eudragit to produce sustained release properties.

For infections of the eye or other external tissues, mouth and skin, the formulations are preferably applied as a topical ointment or cream containing the active ingredient in an amount of for example, 0.075 to 20% w/w, preferably 0.2 to 15% w/w and most preferably 0.5 to 10% w/w. When formulated in an ointment, the active ingredients may be employed with either a paraffinic or a water-miscible ointment base.

Alternatively, the active ingredients may be formulated in a cream with an oil-in-water cream base or as in a water in oil base.

WO 96/06844 PCTGB95/02014 -6- If desired, the aqueous phase of the cream base may include, for example, at least w/w of a polyhydric alcohol, i.e. an alcohol having two or more hydroxyl groups such as propylene glycol, butane-1,3-diol, mannitol, sorbitol, glycerol and polyethylene glycol and mixtures thereof. The topical formulations may desirably include a compound which enhances absorption or penetration of the active ingredient through the skin or other affected areas. Examples of such dermal penetration enhancers include dimethylsulphoxide and related analogues.

The oily phase of the emulsions of this invention may be constituted from known ingredients in a known manner. While this phase may comprise merely an emulsifier (otherwise known as an emulgent), it desirably comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier which acts as a stabiliser. It is also preferred to include both an oil and a fat. Together, the emulsifier(s) with or without stabiliser(s) make up the so-called emulsifying wax, and the wax together with the oil and/or fat make up the so-called emulsifying ointment base which forms the oily dispersed phase of the cream formulations.

Emulgents and emulsion stabilisers suitable for use in the formulation of the present invention include Tween 60, Span 80, cetostearyl alcohol, myristyl alcohol, glyceryl mono-stearate and sodium lauryl sulphate.

The compound (1S,4R)-is-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclo pentene-1-methanol can be synthesised in accordance with European Patent Specification Number 0434450 or alternatively PCT Application No. GB/9500225 which are incorporated herein by reference.

Succinic acid is commercially available (Aldrich Chemical Company, Dorset, England).

Example A Preparation of (1S,4R)-s-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol Succinate Salt.

WO 96/06844 PCTIGB95/02014 -7- A solution of (1S,4R)-is-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol (30.93 g, 0.102 mole) in absolute ethanol (96 mL) was added to a solution of succinic acid (Aldrich, 99%, 12.15 g, 0.102 mole) in water (130mL). The mixture was brought to reflux and the resulting solution was treated with charcoal (0.4 g) and filtered through a Celite pad. Pale yellow crystals (38.0 g) formed as the solution cooled slowly to ambient temperature. This solid was recrystallized from water (500 mL) to give (1S,4R)-is[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2cyclopentene-1-methanol succinate as a white powder (34.9 g, m.p. 168-169oC; 1 H-NMR (DMSO-d 6 12.70-11.70 (brm, 2, 2 carboxyl 7.62 1, purine CH), 7.30 J 4.1Hz), 6.10 1, 5.90- 5.75 3,=CH and NH 2 5.40 1, NCH), 5.20-4.50 (br m, 1, OH), 3.46 J 5.9 Hz, 2, OCH 2 3.10 (br m, 1, CH of cyclopropyl), 2.85 (br m, 1, CH), 2.70-2.50 1, CH), 2.40 4, 2 CH 2 of succinate), 1.70-1.50 1, CH), 0.75-0.50 4, 2 CH 2 of cyclopropyl).

Anal. Calcd. for C14H 18

N

6 0.C4H604.050

H

2 0: C, 52.29 H, 6.09; N, 20.33. Found: C, 52.33; H, 6.09; N, 20.38.

Example B: Tablet Formulations The following formulations A, B and C are prepared by wet granulation of the ingredients with a solution of povidone, followed by addition of magnesium stearate and compression.

Formulation A m/tablet me/tablet Active ingredient 250 250 Lactose B.P. 210 26 Povidone B.P. 15 9 Sodium Starch Glycollate 20 12 Magnesium Stearate 3 500 300 WO 96/06844 PCT/GB95/02014 -8- Formulation B mg/tablet me/tablet Active ingredient 250 250 Lactose 150 Avicel PH 101 60 26 Povidone B.P. 15 9 Sodium Starch Glycollate 20 12 Magnesium Stearate 5 3 500 300 Formulation C (Controlled Release Formulation) The formulation is prepared by wet granulation of the ingredients (below) with a solution of povidone followed by the addition of magnesium stearate and compression.

mg/tablet Active Ingredient 500 Hydroxypropylmethylcellulose 112 (Methocel K4M Premium) Lactose B.P. 53 Povidone B.P.C. 28 Magnesium Stearate 7 700 Capsules are prepared by dispersing the active ingredient in the lecithin and arachis oil and filling the dispersion into soft, elastic gelatin capsules.

Formulation C (Controlled Release Capsule) The following controlled release capsule formulation is prepared by extruding ingredients a, b, and c using an extruder, followed by spheronisation of the extrudate and drying. The dried pellets are then coated with release- controlling membrane (d) and filled into a two-piece, hard gelatin capsule.

I

PCT/GB95/02014 WO 96/06844 -9- Active Ingredient Microcrystalline Cellulose Lactose BP Ethyl Cellulose mgcapsule 250 125 125 13 513 Example D: Injectable Formulation Active ingredient -Sterile, pyrogen free phosphate buffer (pH 7.0) to 0.200g 10 mi 0 The active ingredient is dissolved in most of the phosphate buffer (35-40 then made up to volume and filtered through a sterile micropore filter into a sterile amber glass vial (type 1) and sealed with sterile closures and overseals.

Example E: Intramuscular Injection Active Ingredient Benzyl Alcohol Glycofurol 75 Water for Injection 0.20 g 0.10 g 1.45 g 3.00 ml q.s. to The active ingredient is dissolved in the glycofurol. The benzyl alcohol is then added and dissolved, and water added to 3 ml. The mixture is then filtered through a sterile micropore filter and sealed in sterile 3 ml glass vials (type 1).

Example F: Active ingredient Sorbitol Solution Glycerol Dispersible Cellulose Syrup Suspension 0.2500 g 1.5000 g 2.0000 g 0.0750 g WO 96/06844 PCT/GB95/02014 Sodium Benzoate 0.0050 g Flavour, Peach 17.42.3169 0.0125 ml Purified Water q.s. to 5.0000 ml The sodium benzoate is dissolved in a portion of the purified water and the sorbitol solution added. The active ingredient is added and dispersed. In the glycerol is dispersed the thickener (dispersible cellulose). The two dispersions are mixed and made up to the required volume with the purified water.

Example G: Suppository mg/suppositorv Active Ingredient (631m) 250 Hard Fat, BP (Witepsol H15 Dynamit NoBel) 1770 2020 *The active ingredient is used as a powder wherein at least 90% of the particles are of 63 pm diameter or less.

One-fifth of the Witepsol H15 is melted in a steam-jacketed pan at 45 0 C maximum.

The active ingredient is sifted through a 200pm sieve and added to the molten base with mixing, using a silverson fitted with a cutting head, until a smooth dispersion is achieved. Maintaining the mixture at 45 C, the remaining Witepsol H15 is added to the suspension and stirred to ensure a homogenous mix. The entire suspension is passed through a 2501m stainless steel screen and, with continuous stirring, is allowed to cool to 40 C. At a temperature of 38 C to 40 C 2.02g of the mixture is filled into suitable plastic moulds. The suppositories are allowed to cool to room temperature.

Examole H: Pessaries mg/pessarv Active ingredient 631m 250 Anhydrous Dextrose 380 Potato Starch 363 Magnesium Stearate 7 1000 -11- The above ingredients are mixed directly and pessaries prepared by direct compression of the resulting mixture. Example I: Topical formulation Cream Active compound Glycerol Cetostearyl alcohol Sodium lauryl sulphate White soft paraffin Liquid paraffin Chlorocresol Purified water 5.00g 2.00g 6.75g 0.75g 2.50g 5.00g 0.lOg to 100.OOg *r Dissolve the active compound in a mixture of purified water and glycerci and heat to 70 C. Heat the remaining ingredients together at 70 C. Add the two parts together and emulsify. Cool and fill into containers.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

-12- Comparative Results Salts of (1 S,4R)-cis-4-2-amino--(cyclopropyfra1ifl)- 9 H-purin-9-y1-2-cydopentene- I -methanol (1 592U89) Salt Yield Comments Succinate 80%M Both starting materials were soluble in EtOH. White solid formed immediately during stirring of 1592U89 and succinic acid in EtOH. Filtration was easy.

Fumnarate 78% Both starting materials were dissolved in EtOAc/EtOH. Offwhite solid formed while stirring 1592U89 and fumaric acid in EtOAcIEtOH, Level of hydration is ill-defined.; takes up water in an uncontrolled manner.

Oxalate Oxalic acid is poisonous and therefore not a pharmacologically L-Tartrate 79% Precipitate formed in EtOH-, but very slowly; hygroscopic.

Citrate low Did not form precipitate in EtOHI but with the addition of EtOAc a small amount of solid was formed.

Dihydrochloride 75% Carried out on 642 gram scale, biologists found it to be too irritating to animals because of acidity; had to add sodium hydroxide to bring solutions to pH 4-5 in order to dose animals; judged too acidic for use in man. This experience prompted exploration of salts of weaker (carboxylic acids, e.g. succinate) which would be less acidic (when dissolved) and therefore less irritating in vivo.

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS 1. The succinate salt of (1S,4R)-cis-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2cyclopentene-1 -methanol.

2. A solvate of the compound as claimed in Claim 1.

3. A hydrate of the compound as claimed in Claim 1.

4. A method for the treatment or prophylaxis of a viral infection in a human which comprises administering to said host an effective amount of the compound claimed in Claim 1.

A method according to claim 4 wherein the viral infection is HIV or HBV infection.

6. Use of a compound as claimed in any Claim from 1 to 3 in the manufacture of a medicament for the treatment or prophylaxis of a viral infection.

7. A process for the preparation of the compound claimed in Claim 1 which comprises i :.mixing (1 S,4R)-cis-4-[2-amino-6-(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene- 1methanol in a suitable solvent with succinic acid in water and at such conditions so as to effect the formation of the compound of Claim 1.

8. A pharmaceutical formulation comprising of a compound claimed in any Claim from 1 to 3 and at least one pharmaceutically acceptable carrier thereto.

9. A pharmaceutical formulation as claimed in Claim 8 formed into a tablet or a capsule.

10. A pharmaceutical formulation as claimed in Claim 8 adapted for parenteral administration.

11. A pharmaceutically formulation according to Claim 8 substantially as hereinbefore described with reference to the Examples.

DATED this THIRTEENTH day of OCTOBER 1998 The Wellcome Foundation Limited.

By its Patent Attorneys DAVIES COLLISON CAVE

Claims

1. The sucdnate salt of (1 S,4R)-d^-4-[2-aniino-6-(cyclopropylamino)-9H-purin- 9-yl]-2-cyclopentene-l-methanol.

2. A solvate of the compound as claimed in Claim 1.

3. A hydrate of the compound as claimed in Claim 1.

4. A method for the treatment or prophylaxis of a viral infection in a human which comprises administering to said host an effective amount of the compound claimed in Claim 1.

5. A compound as claimed in any Claim from 1 to 3 for use in medical therapy.

6. Use of a compound as claimed in any Claim from 1 to 3 in the inanufacture of a medicament for the treatment or prophylaxis of a viral infection

7. A process for the prepration of the compound claimed in Claim 1 which comprises mixing (lS,4R)-cjfi-4-[2-anιmo-6-(cyclopropyhιπjino)-9H-pur yl]-2-cydopentene-l-methanol in a suitable solvent with sucαnic add in water and at such conditions so as to effect the formation of the compound of Claim 1.

8. A pharmaceutical formulation comprising of a compound claimed in any Claim from 1 to 3 and at least one pharmaceutically acceptable carrier thereto.

9. A pharmaceutical formulation as claimed in Claim 8 formed into a tablet or a capsule.

10. A pharmaceutical formulation as claimed in Claim 8 adapted for parenteral administration.